1. Field of the Invention
This invention relates to a multi-metering device for dividing an object field or scene into a plurality of areas and metering the plurality of areas and operating and extracting, from a plurality of photoelectric outputs corresponding to said plurality of areas, a proper metering output for determining the proper exposure of an entire picture plane.
2. Description of the Prior Art
As a metering device of such type, there has been known a device in which the arithmetical mean value of the maximum value and the minimum value of a plurality of photoelectric outputs is used as a proper metering output (Japanese Utility Model Publication No. 9271/1976), or a device in which an intermediate value between said maximum value and said minimum value is manually extracted by the photographer and such intermediate value is used as a proper metering output (Japanese Laid-open patent application No. 17725/1978).
However, these devices according to the prior art suffer from the following disadvantages. In the former device, the exposure is determined by the arithmetical mean value and therefore, for example, in the case of counter-light condition or a special object field condition in which the major object lies on snow, for example, the major object may sometimes become under-exposed or over-exposed. Also, in the latter device, not only is skill required to set the intermediate value so as to provide a proper exposure in the case of the aforementioned special object field condition, but also the setting operation is manually effected and so, when the device is mounted in a camera, the operability thereof is unavoidably reduced.
Further, there is a device in which the exposure determining mode is changed over depending on whether or not the difference between the maximum value and the minimum value of the photoelectric outputs has exceeded a certain value (U.S. Pat. No. 4,214,826), but it is often impossible to judge the condition of the object merely from the brightness difference in the picture plane. For example, between the case of a counter-light scene in which the sun is photographed and the case of theatrical stage photography effected under a spot light, the brightness difference in the picture plane is of the same degree, but a proper exposure cannot be obtained unless the exposure determining systems are made different. In such case, it is necessary to use the maximum brightness value in the picture plane as the material for judgment and to judge by what kind of object that high brightness is being created.
Incidentally, as the reason why the object field is divided into a plurality of areas and the plurality of areas are metered, it may be mentioned that a proper exposure is obtained even in counterlight photography. However, when a high brightness portion such as the sun has come into the picture plane, an under-exposure photograph has resulted according to the conventional devices. This is because, although the high brightness portion occupies only a part of the picture plane, the absolute amount of its brightness is greater than that of the major object and even if the brightnesses of the two is averaged, the average value becomes considerably greater than the brightness of the major object.
On the other hand, where a plurality of photoelectric outputs corresponding to the plurality of areas are obtained, part of the picture plane is below the lower limit of metering but the remaining portion can sometimes be metered. For example, this occurs in a case where the object is illuminated by a spot light. The conventional devices have been almost ineffective for this.
Further, where the contrast in the picture plane is high, if the exposure is controlled for the high brightness portion or for the low brightness portion, there may result a photograph in which the low brightness portion or the high brightness portion has been defaced so as to give a sense of unpleasantness to the viewer of the photograph.